Z-pin增强复合材料层合板断裂韧性试验研究

Experimental investigation on the fracture toughness of Z-pins reinforced composite laminates

针对Z-pin增强复合材料层合板,开展了断裂韧性的试验研究。研究选取了3种Z-pin直径(0.28、0.52、0.80 mm)且每种直径下分别以3种分布形式(5×5、8×8、10×10)排布Z-pin的增强方式,为了确定比较基准,试验中同时测试了不含Z-pin的复合材料层合板试样。通过Z-pin拔出试验测试了3种直径Z-pin从基体拔出过程中的载荷-位移关系。利用双悬臂梁试验和端部开口弯曲试验分别测试了不含Z-pin和含Z-pin试样的Ⅰ型断裂应变能释放率G_(ⅠC)、Ⅱ型断裂应变能释放率G_(ⅡC)。试验结果表明:与不含Z-pin的结构相比,Z-pin增强试样的Ⅰ型断裂应变能释放率G_(ⅠC)增大了83%～1110%,Ⅱ型断裂应变能释放率G_(ⅡC)增大了23%～438%;在相同Z-pin体积含量下,与增大Z-pin直径相比,增大Z-pin分布密度能更有效地提高复合材料层合板的断裂韧性。

The fracture toughness experiments of Z-pin reinforced composite laminates were carried out. Pull-out test of Z-pins of different diameters（0.28, 0. 52, 0. 80 mm）embedded into unidirectional laminate coupons was conducted to measure the curves of Z-pin bridging force versus pull-out displacement. Then, the mode I and mode II fracture toughness of Z-pinned laminates and unpinned laminates were tested respectively using the double- cantilever-beam （DCB） method and three point edge-notched-flexure （ENF） methods. Comparison was made for the measured mode I and mode II strain energy release rates between two types of laminates. Strain energy release rates GIC and GIC of Z-pin reinforced laminates are higher from 83% to 1110% and from 23% to 438% than those of unpinned laminates respectively. Moreover, the test results denote that enlarging the Z-pin distributive density is more effective to reinforce structural strain energy release rate than enlarging Z- pin diameter at the same volume fraction.